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Final Notes.doc

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BIOL 1070
Wright& Newmaster

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BIOL 1070 Final – Notes Course Notes Weeks 1-3 1. Mussels of the great lakes region (Evolution) Weeks 4-7 2. Forest biodiversity (Evolution and Ecology) Weeks 9-13 3. Arctic ecosystem (Evolution, Ecology, and Physiology) Evolution: study of both adaptive and non-adaptive change over time in populations, the origin and extinction of species, and the relationship among living things. Ecology: study of interrelationships between organisms and both living (biotic) and non-living (abiotic) components of their environments. Physiology: study of organism structure and function, including homeostasis and encompassing cells, tissues, organs, and body systems. Impact of climate change on arctic ecosystem – Why be concerned? Polar ice caps melting, sea level rising. Less ice = more absorbtion of UV rays + heat by the ocean and land. Less available land when ice melts (sea level rises) = more densely populated. 1. Biological impacts (biodiversity changes, disease, migration) 2. Political and economic impacts (arctic sovereignty, natural resources, environmental policy) 3. Aesthetics (landscapes, tourism) 4. Cultural changes (traditional hunting practices) What are the consequences of an arctic ecosystem 8 degrees warmer? 1. key abiotic variables in arctic 2. examples of arctic plants and animals 3. how temperature changes impact organisms at different levels of organization What we need to know 1. how climate change impacts organisms on different time scales 2. how climate change impacts plants and lichens 3. physiological responses to temperature change in animals 4. predicting long term trends in arctic populations 1 - How climate change impacts organisms on different time scales Example Question: Arctic fox remain active when arctic temperatures fall to -50 degrees. Several strategies for surviving this climate are listed below. Select the physiological strategy that is correctly matched with a time scale and level of organization. Answer: E) Arctic fox has small ears, a short muzzle, relatively short legs and a small rounded body that limits heat loss in the cold (= generational, whole organism) Time domains for temperature change Arctic plants and animals have lived in the arctic ecosystem for thousands of years. They must cope with temperature change on many different time scales: Acute, Chronic, and Generational. What you need to know: -is the organism unicellular or multicellular? -is the animal an endotherm or ectotherm? -is the animal able to avoid the temperature change? -are there behavioural responses that the animal can invoke to reduce the impact of the temperature change? -what types of physiological responses are possible and at what level (cell, tissue, organ, etc.)? 1. Acute response: Increase in ambient temperature, regulation or increase in body temperature 2. Chronic response: Chronic stress, Physiological (acclimatization to new thermal regime), population range changes 3. Generational response: Extirpation or extinction, natural selection (adaptation to new thermal regime) Acclimatization: adjustment by individual to chronic stress, physiological processes change to better function under new conditions, change is reversible and may be reversible -ULT shifts because winter fish acclimatize to a lower range of temperatures relative to summer fish Question: Do mush ox acclimatize to seasonal changes in climatic conditions? Answer: Ox pelage goes through seasonal changes, migrate down to lowlands in winter, highlands in summer. Structure is linked to function -parallel arrangements of vessels -tissue levels -countercurrent flow Reconstruction of hemoglobin of wooly mammoth: Level of organization: Macromolecule Hypothesis: Wooly mammoth hemoglobin had properties that allowed it to function in cold extremities and appendages, despite having a warmer core temperature. Prediction: Hemoglobin structure will be more similar to that of arctic animals than closely related tropical elephants. Results: WM hemoglobin unloaded oxygen more efficiently in colder conditions than hemoglobin from living elephants. Implications: Biochemical specialization may have been involved in the exploitation of high latitude environments by this African derived elephantid species during Pleistocene period. 2 – How climate change impacts plants and lichens Adaptations in arctic plants and lichens What abiotic factors challenge arctic plants? What are the adaptations of arctic plants? At minimum, what do ALL plants need to survive and reproduce? -Chloroplast: Thylakoid membrane, Starch grain -Vacuole: Vacuole, Tonoplast -Nucleus: Nuclear pore, Nuclear envelope, Nucleus 3 – Physiological responses to temperature change Classifying animals in terms of responses to environment In ectotherms, the Q10 provides a measure of how sensitive metabolic processes are to temperature change. Q10 can be determined on any rate process (breathing rate, heart rate, metabolic rate) Conformer: allow the internal environment to follow changes in the external environment. Regulator: regulators maintain a constant internal environment (homeostasis) in the face of a varying external environment. Can an animal be both a conformer and a regulator? Thermocontrollers, but regulate the constant internal ion concentration. Heterothermy: Endothermic at certain times or in certain tissues but not at all times or in all tissues. Ex. Different times: humming birds daily hibernation Different tissues: Bumble bees thorax is hotter than other parts Metabolic rate and temperature graph: Left = ectotherms, right = endotherms -When it gets cold, oxygen consumption increases because the body needs more energy and oxygen to stay warm. When you’re overheated, your body uses energy + oxygen to stay cold. Ectothermy Cost: dependent on environment, can’t always perform to maximum levels Benefit: don’t have to spend energy to maintain core temperature Endothermy (Bergman’s rule) Body size tends to be larger for species of endotherms living in the cold. (Low surface area : volume – ratio = easier to retain heat.) Arctic Fox: acclimatized to summer conditions begin to increase oxygen consumption at a higher ambient temperature than foxes acclimatized to winter conditions. This may relate to differences in the insulating properties of their fur in different seasons. 3 - Physiological responses to temperature change in animals Animals can gain or lose heat in many different ways: 1. Radiation 2. Conduction 3. Convection 4. Evaporation Skin circulation: Heat Production: -muscle activity -shivering -non-shivering thermogenesis -digestion 4 – Predicting long term trends in arctic populations Supercooling and Ice Nucleation -Pure water can be cooled to below 0 degrees without freezing -Physical disruption or addition of an ice-nucleating agent causes rapid freexing of supercooled water Freezing-point depression: colligative antifreezes Solution of water freezes at 0 degrees, colligative antifreezes lower freezing point of body fluids by increasing concentration of solutes. Freezing-point depression: noncolligative antifreezes Noncolligative antifreezes lower the freezing point of body fluids because of specialized chemical properties. *Strategies for overwintering in ectotherms What strategies do arctic ectotherms use to survive winter conditions? Strategies Freeze tolerance Freeze intolerance 1. behavioural avoidance 2. production of antifreeze compounds 3. synthesis of ice nucleating agents 4. supercooling (temperate NOT arctic species) Thinking like a biologist Observation: Antifreeze proteins increase in fall and decrease in spring in arctic marine fishes Question: What is the trigger for synthesis of antifreeze proteins in arctic marine fish? Hypothesis: In cold water marine fish, the trigger for synthesis of antifreeze protein is……. Prediction: If so then…… What are the consequences of an Arctic ecosystem 8C warmer? Physiology : the biological impact of rising temperatures depends on the physiological sensitivity of organisms to temperature change. Evolution and ecology: biological impact of rising temperatures also depends on differences in survival and/or reproduction among individuals on the basis of differences in heritable traits/characteristics as these individuals interact with each other and their environment -tundra and tropical forest ecosystems will loose the greatest number of species because these ecosystems have high richness and slight changes in temperature will disrupt fine-scaled climatic gradients -Arctic ecosystems will gain the greatest number of species because these ecosystems have low richness and slight increases in temperature will create new niches allowing many species to establish -Arctic ecosystems will have the highest rates of species turnover as entirely new communities and ecosystems establish (forest, wetlands) with slight increases in temperature What is richness? Count of species Will there be bears? What information do you consider to be the most important in determining if there will be bears in the arctic following the current trend in climate change? -migration -food source -competition Is there available habitat? Can bears move long distances? Can bears change their ecology? -polar bears can probably den successfully in other than permafrost features, but will this affect reproductive success?
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